Multilateral well systems are well known in the oil and gas industry. Generally, a multilateral well system includes a primary wellbore formed through a formation and one or more lateral wells that extend from the primary wellbore into the adjacent formation. Multilateral well systems enjoy several advantages, including, among others, higher production indices, which increases profitability on low producing wells.
While multilateral well systems enjoy certain advantages, they suffer from several problems that have plagued the industry. In particular, drilling and completing a multilateral well system presents several problems, including sealing the junction between the laterally formed wellbore and the primary wellbore. Without a good seal between the lateral and primary wellbores, the junction is highly prone to leaking, causing a host of problems. For instance, an improperly sealed junction may not allow effective zone isolation, which is an important component to well completion. And an improperly sealed junction is prone to undesirable sand intrusion from unconsolidated sand surrounding the wellbore.
Several methods and systems have been developed and employed to provide reliable junction seals between the primary and lateral wellbores. While these existing systems and methods fulfill their respective, particular objectives and requirements, they are not without drawbacks. For example, many existing systems require removing a complete segment of well casing at the junction location. Removing well casing is undesirable because the formation surrounding the junction becomes unsupported by the well casing, thereby risking collapse of the formation. Additionally, many existing systems require complex and specialized well completion equipment and, further, prevent full well casing drift.
Accordingly, a need remains for a new multilateral well system and method that provides a reliable junction seal without removing well casing and that maintains full well casing drift.